A hospital supported by the Doctors Without Borders (MSF) in Yemen has been hit by a rocket killing at least four people, the charity says.

Hospitals in Yemen on brink of shutting down

The incident on Sunday, in the northern governorate of Saada near the Saudi Arabian border, also left another 10 people injured, the group said.

In a series of tweets, MSF said it was the third "serious incident" in as many months affecting its facilities in the country.

"We strongly condemn this and we reiterate to all parties to the conflict that patients & medical facilities must be respected," a statement by MSF on Twitter said about the incident in the town of Razeh.

The organisation did not say who was behind the attack, but that "planes were seen flying over the facility at the time".

"All parties to the conflict, including the Saudi-led coalition, are regularly informed of the GPS coordinates of the medical sites where MSF works, " said Raquel Ayora, MSF Director of Operations.

"We are in constant dialogue with these parties to ensure that they understand the severity of the humanitarian consequences of the conflict and the need to respect the provision of medical services.

"There is no way that anyone with the capacity to carry out an air strike or launch a rocket would not have known that the Shiara Hospital was a functioning health facility providing critical services and supported by MSF."

#Yemen: This is the 3rd severe incident in the last 3 months. Our teams struggle on a daily basis to ensure the respect of health facilities

Saada province is a stronghold of Houthi rebels, who are at war with the Yemeni government and an Arab military coalition, which includes Saudi Arabia.

In October, a hospital in Saada province run by MSF was hit by what it said was a coalition air strike - a claim the coalition denied.

Speaking to Al Jazeera at the time, MSF spokesman Hassan Boucenine said the attack "must have been deliberate", as the group had provided the coalition with the coordinates of its facility in Saada.

Humanitarian crisis

Yemen is facing a humanitarian crisis brought on by the war between the Houthis and pro-government forces.

Hospitals across the country are warning they are running low on essential equipment and are on the brink of shutting down.

The UN said in December that food supplies in the country were depleting rapidly and that up to half of the country was facing famine.

Yemen's ongoing conflict started in March last year when Arab forces intervened to restore the government of President Abd-Rabbu Mansour Hadi, who fled when Houthi rebels took over the souther port city of Aden.

The conflict has killed almost 6,000 people so far according to the UN.